A microfilm image processing apparatus is known which uses a single zoom lens for projecting an image-carrying beam of light onto a target plane A full range of magnification/reduction ratio which is desired for a microfilm image processing apparatus could not however be achieved in an apparatus of such a type since only a limited range of magnification can however be obtained with a single zoom lens.
It has therefore been proposed a microfilm image processing apparatus using a zoom lens detachably fitted into the apparatus and thus exchangeable with another zoom lens. A zoom lens having a desired range of magnification can thus be fitted to the apparatus so that a beam of light is projected from the selected lens with a magnification/reduction ratio within a range proper to the particular lens.
Thus, a prior-art image processing apparatus of type using a detachable zoom lens has a drawback in that the operator is required to follow a troublesome procedure in exchanging a lens with another. The present invention contemplates elimination of this drawback through provision of a plurality of zoom lenses having different ranges of magnification and readily interchangeable with one another depending on a desired magnification/reduction ratio.